This invention relates to a shaper guard, and more particularly to a shaper guard having a gravity-biased guard panel.
A shaper, as used in the art of woodworking, includes a rotary cutter head having peripheral cutting edges or knife tips in a particular shape, so that when the shaper head is rotated, the continuous elongated shape or contour may be formed in the surface of a wooden workpiece engaging the shaper head. The shaper head is usually mounted on a vertical spindle which is power-driven and projects above the horizontal planar work surface of a table. A pair of upright fences or guide surfaces for the workpiece are mounted in longitudinal alignment, but spaced from each other on opposite sides of the peripheral path of the shaper head. A wooden workpiece, such as an elongated board or plank is manually held against one fence and moved toward the rotating shaper head so that the edge of the board is engaged and shaped by the shaper head.
The above described process is very dangerous, since the wooden workpiece has to be held manually at all times, thus exposing the hands and fingers of the operator to being cut by the shaper head if the hands or the workpiece slip. In fact, such an accident has occurred to the Applicant, resulting in the loss of parts of four fingers.
Because of the high degree of danger in the operation of shaper heads in woodworking, various attempts to provide shaper guards have been made.
The following U.S. patents disclose various types of shaper guards and/or linear-type clamping bars utilized on cutting or shaping machines:
______________________________________ 300,363 Harps June 17, 1884 883,148 Sanders Mar. 24, 1908 938,273 Richards Oct. 26, 1909 1,183,566 Jessrang May 16, 1916 4,499,933 Thompson Feb. 19, 1985 ______________________________________
Every one of the guards or clamping bars disclosed in the above patents includes a spring for biasing the guard or clamp piece downward to assist in holding the workpiece upon the table as it is moved in engagement with the cutter head or shaper head.
Both the Harps and the Jessrang patents disclose elongated guard bars having opposite curved ends to facilitate camming of the guard bar upward when engaged by the wooden workpiece.
Harps and Sanders disclose single elongated guards or clamp pieces. Moreover, the clamping board 19 of Sanders is primarily designed for holding the workpiece rather than for guarding or protecting the operator from the cutting knives.
The Richards patent discloses a circular or partially circular guard 5 having a rotary guard piece or chip breaker 15 and a pivotal work clamping member 12 (FIGS. 1-6); 23 (FIG. 7); and 26 (FIG. 8).
Although the Jessrang patent discloses a two-piece guard member including a vertically movable guard 22, nevertheless, the guard 22 is biased downwardly by the leaf spring 24.
The two-piece guard members disclosed in Thompson are biased downward by springs and also are so widely separated from each other that no protection is afforded to direct access of the operator's hands into the cutting area of the shaper head.
The following U.S. patents disclose various types of shaper guards in the form of rings surrounding the cutter or shaper head:
______________________________________ 720,039 Lemmon Feb. 10, 1903 822,636 Steer June 5, 1906 907,734 Butterfield Dec. 29, 1908 1,025,866 Erickson May 7, 1912 2,642,104 Brown June 16, 1953 ______________________________________
All of the above ring guards are biased downward by springs.
Of all of the above patents disclosing both linear and ring guards, none of them, except Brown, disclose a guard member normally resting upon the work surface.
Accordingly, none of the above patents disclose a two-piece linear shaper guard including a fixed elongated guard body within which is mounted a vertically movable guard panel biased downwardly by gravity to a normally inoperative position resting upon the table surface, to substantially completely encompass the shaper head and prevent access to the shaper head cutting area by the hand or fingers of the operator.